1. Field of the Invention
This invention relates to optical image processing.
2. State of the Prior Art
There are situations in which useful information can be derived from spatially dispersed portions of light beams. In particular, when an image is being carried or propagated by a light beam, it may be useful to gather and use or analyze information from a particular portion of the image, such as from a particular portion of a cross-section of a beam that is carrying an image. For example, in my U.S. Pat. Nos. 6,678,411 and 7,103,223, which are incorporated herein by reference, narrow, radially oriented portions of a Fourier transform of an image are captured and detected in the spatial domain and used to characterize and encode images by shape for storage, searching, and retrieval. As explained therein, such radially oriented, angularly or rationally spaced portions of light energy from a Fourier transform, i.e., Fourier transform domain, of an image are captured sequentially in the spatial domain, and such portions of the light energy detected in the spatial domain are characteristic of the portions of the image content that are generally linearly aligned in the same angular orientation as the slit in the rotating mask when the light energy is detected. Those systems perform the task of characterizing and encoding images by shape content of the images quite well, but they still have several troublesome shortcomings. For example, the optical systems are quite rigid with little flexibility or tolerance for imperfections in practical optical components or in selection and placement of such components in relation to each other, which results in inherent limitations that constrain the output to less than desirable quality and impose constraints on overall size, optical layout, cost, and packaging.